1. Field of the Invention
The present invention relates to waveguide rotary joints enabling the transmission of microwave signals, for example between a high-frequency radar head placed in a turret rotating about a frame and other circuits of the radar housed in the frame.
This type of microwave rotary joint is generally associated with an electrical rotary joint with slip-ring collector enabling the electrical supply, from the frame, to the instruments placed in the turret, and the exchange of various electrical information signals between the instruments housed in the turret and those housed in the frame.
2. Description of the Prior Art
The transmission of electrical information signals by means of the slip-rings of the collector of the electrical rotary joint is difficult because such transmission is sensitive to the parasites generated by brushes and by the proximity of the supply currents. It calls for many precautions:
- contacts by several brushes PA0 - protection against oxidation in order to prevent contact defects; PA0 - careful distribution of the power slip-rings on the collector in order to restrict parasitic interference with the electrical information signals and, in the event of mechanical malfunctioning, to prevent a possibility of contact between the power slip-rings and the wires conveying the electrical information signals; PA0 - arrangements have to be made for a high quality ground return. PA0 - a part known as a fixed part, PA0 - a part known as a rotating part in rotation about an axis .DELTA. in relation to the fixed part, PA0 - at least one pair of microwave guide inputs, one of which is positioned in the fixed part while the other is positioned in the rotating part, these microwave guide inputs being coupled to each other by a coaxial link placed along the rotation axis .DELTA., said coaxial link being provided with a conductive core that has a first end fixed in the rotating part and a second end sliding rotationally in the fixed part, PA0 - an optic fiber fixedly joined to the rotating part, that penetrates said rotating part and goes through the conductive core of the coaxial link in the longitudinal direction along a channel made along the rotational axis .DELTA. in the direction of the fixed part, PA0 - and an optic coupling means that is fixedly joined to the fixed part and is centered on the rotation axis .DELTA. facing the end of the optic fiber that is fixedly joined to the rotating part.
The effect of all these precautions is to make the electrical rotary joint heavy and bulky. Furthermore, the throughput rate possible for information exchanges by means of an electrical signal remain limited. This may entail a great increase in the number of communication channels and a further increase in the bulk of the electrical rotary joint.
The present invention is aimed at overcoming these drawbacks by providing for the association of the microwave rotary joint with an optic rotary joint having an optic fiber.
The use of a link by optic fiber and optic rotary joint has the advantage of enabling a mode of transmission of information signals that is insensitive to parasitic phenomena and to parasitic noises from the power slip-rings. Furthermore, the transmission rate may attain far greater values.